U.S. patent number 4,722,410 [Application Number 06/878,902] was granted by the patent office on 1988-02-02 for obstacle detection apparatus.
This patent grant is currently assigned to Caterpillar Industrial Inc.. Invention is credited to Joseph J. Harding, Grant C. Melocik.
United States Patent |
4,722,410 |
Melocik , et al. |
February 2, 1988 |
**Please see images for:
( Certificate of Correction ) ** |
Obstacle detection apparatus
Abstract
Collision detection systems are commonly provided on automatic
guided industrial vehicles. Such systems should be as reliable as
possible and can advantageously utilize a fault detection
apparatus. The subject apparatus provides a plurality of radiant
energy emitting devices and receiving devices positioned along a
vehicle at locations sufficient that an obstacle in a respective
path of the vehicle interrupts the reception of radiant energy by
respective ones of the receiving devices. Interruptable devices
controllably connect a power supply to a brake control circuit in
response to continuous reception of radiant energy by the
respective receiving devices, and disconnect the power supply from
the brake control circuit in response to any of the receiving
devices failing to continue to receive radiant energy from the
respective emitting device. A vehicle control circuit controllably
produces first and second energization signals in response to a
predetermined condition of the vehicle, and first and second
switches receive respective ones of the first and second
energization signals and responsively controllably supply
electrical power from the power supply to predetermined ones of the
emitting devices and the receiving devices.
Inventors: |
Melocik; Grant C. (Chardon,
OH), Harding; Joseph J. (Mentor, OH) |
Assignee: |
Caterpillar Industrial Inc.
(Mentor, OH)
|
Family
ID: |
25373062 |
Appl.
No.: |
06/878,902 |
Filed: |
June 26, 1986 |
Current U.S.
Class: |
180/169; 180/275;
303/20 |
Current CPC
Class: |
B60T
7/22 (20130101); B60R 19/02 (20130101); B60Q
9/008 (20130101); B60K 31/0008 (20130101); G01S
17/931 (20200101) |
Current International
Class: |
B60K
31/00 (20060101); B60Q 1/52 (20060101); B60Q
1/50 (20060101); B60T 7/22 (20060101); B60R
19/02 (20060101); G01S 17/00 (20060101); G01S
17/93 (20060101); B60T 007/12 () |
Field of
Search: |
;180/167,169,275
;188/171 ;303/20,92 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Love; John J.
Assistant Examiner: Mar; Michael
Attorney, Agent or Firm: Noe; Stephen L.
Claims
We claim:
1. Apparatus for detecting failure of an obstacle sensing device
associated with a vehicle, said vehicle having a power supply and a
vehicle brake and brake control circuit, comprising:
a plurality of radiant energy emitting devices each associated with
a respective radiant energy receiving device;
a vehicle control means for controllably producing first and second
energization signals in response to a predetermined condition of
said vehicle;
first and second switch means for receiving respective ones of said
first and second energization signals, and responsively
controllably supplying electrical power from said power supply to
predetermined ones of said radiant energy emitting and receiving
devices;
first and second solenoid coils each serially connected to
respective first and second sets of radiant energy receiving
devices, said first and second sets of radiant energy receiving
devices being mutually exclusive;
first and second electrical contact sets serially connected between
said power supply and said brake control circuit, each of said
first and second electrical contact sets being responsive to a
respective one of said first and second solenoid coils; and
logic mean for controllably producing a fault signal in response to
failure of at least one of said radiant energy emitting devices,
said radiant energy receiving devices, said first and second
solenoid coils, and said first and secnd electrical contact
sets.
2. Apparatus for sensing an obstacle in the path of a vehicle, said
vehicle having a power supply, a vehicle control circuit, and a
vehicle brake and brake control circuit, comprising:
a plurality of radiant energy emitting means for controllably
producing radiant energy;
a plurality of radiant enerty receiving means for receiving said
radiant energy, each of said radiant energy receiving means being
optically responsive to a predetermined one of said radiant energy
emitting means, and wherein eahc optically responsive set of said
radiant energy emitting means and a radiant energy receiving means
is positioned along said vehicle at a location sufficient that an
obstacle in a respective path of said vehicle interrupts the
reception of said radiant energy by said respective responsive
radiant energy receiving means;
first and second interruptible means for controllably connecting
said power supply to said brake control circuit in response to each
of said radiant energy receiving means continuing to receive sasid
radiant energy from said respective radiant energy emitting means
and disconnecting said power supply from said brake control circuit
in response to any of said radiant energy receiving means failing
to continue to receive said radiant energy from said respective
radiant energy emitting means, wherein said first interruptible
means includes a first solenoid coil serially connected with a
first set of said plurality of radiant energy receiving means and a
first electrical contact set serially connected between said power
supply and said brake control circuit, and said second
interruptible means includes a second solenoid coil serially
connected with a second set of said plurality of radiant energy
receiving means and a second electrical contact set serially
connected between said power supply and said brake control circuit,
said first and second sets of radiant energy receiving electrical
contact sets being responsive to a respective one of said first and
second solenoid coils; and
logic means for controllably producing a fault signal in response
to failure of at least one of said radiant energy emitting means,
said radiant energy receiving means, and said first and second
interruptible means, wherein said logic means includes a logic gate
having a first input terminal connected to one of said first ad
second electrical contacts sets, a second input terminal connected
to the other of said first and second electrical contact sets, and
an output terminal connected to said vehicle control circuit.
3. Apparatus for detecting failure of an obstacle sensing device
associated with a vehicle, said vehicle having a power supply and a
vehicle brake and brake control circuit, comprising:
a plurality of radiant energy emitting devices each associated with
a respective radiant energy receiving device;
a vehicle control means for controllably producing first and second
energization signals in response to a predetermined condition of
said vehicle;
first and second switch means for receiving respective ones or said
frist and second energization signals, and responsively
controllably supplying electrical power from said power supply to
predetermined ones of said radiant energy emitting and receiving
devices;
first and second solenoid coils each serially connected to
respective first and second sets of radiant energy receiving
devices, said first and second sets of radiant energy receiving
devices being mutually exclusive;
first and second electrical contact sets serially connected between
said power supply and said brake control circuit, each of said
frist and second electrical contact sets being responsive to a
respective one of said first and second solenoid coils; and
logic means for controllably producing a fault signal in response
to a failure of at least one of said radiant energy emitting
devices, said radiant energy receiving devices, said first and
second solenoid coils, and said first and second electrical contact
sets, wherein said logic means includes a logic gate having a first
input terminal connected to one of said first and second electrical
contact sets, a second input terminal connected to the other of
said first and second electrical contact sets, and an output
terminal connected to said vehicle control means.
Description
TECHNICAL FIELD
This invention relates generally to an apparatus for detecting
obstacles in the path of a vehicle, and more particularly, to an
apparatus for detecting failure of an element associated with an
obstacle detection device.
BACKGROUND ART
Automatic guided vehicles operating without the assistance of a
human operator are in common commercial use today. Such vehicles
require sophisticated collision detecting devices to prevent
contact between the vehicle and objects in the area surrounding the
vehicle. Obstacle detection systems of various designs have been
employed in the past. Systems utilizing the transmission and
reception of radiant energy have proven particularly suitable for
this task. For example, U.S. Pat. No. 3,664,701 issued May 23, 1972
to Lewis Kondur is typical of one such system. The Kondur device
includes a light source mounted on the vehicle directed toward a
retroreflective target mounted on a movable bumper associated with
the vehicle. Under normal circumstances, energy from the light
source is directed back along the identical path from the target to
a light receiving device. In response to contact between the
movable bumper and an external object, the retroreflector is moved
relative to the light source and the energy is no longer detected
by the receiving device.
Bumper systems such as that described above are adequate for
detecting certain classes of obstacles. However, such systems fail
to detect objects encroaching from the sides or rear of a vehicle.
In addition, owing to the high degree of reliability required for
obstacle detection systems, it is desirable to employ some form of
failure protection apparatus in association with the obstacle
detection system.
Some initial attempts to provide such failure protection devices
are known in the art. For example, U.S. Pat. No. 3,560,922 issued
Feb. 2, 1971 to U.S. Pat. No. 3,560,922 issured Feb. 2, 1971 to
Kenneth A. Wilson incorporates a simple contact switch type bumper
system. In response to contact between a bumper and an external
object, a switch contact is closed, producing a stop signal. The
stop signal is also produced in response to failure of one of the
wire connections to the bumper switch. Another example of a failure
detection system is found in U.S. Pat. No. 4,087,782 issued May 2,
1978 to Kazuo Oishi, et al. A collision detecting system has a
bumper inductively coupled to an oscillator circuit. A "checking"
switch is employed to selectively operate the detection system in a
"check" mode. While in the "check" mode, a warning is provided in
response to detecting an open circuit in the lead wires of a sensor
and to detecting failure of the oscillator circuit.
None of the prior systems known in the art adequately detects
failures associated with an optical collision detection device.
Such a failure protection device should advantageously detect both
open and short circuit conditions associated with the collision
detection system, and should responsively produce a signal
indicating such failure. It is further desirable that the failure
detection system operate automatically upon each start up of the
vehicle.
The present invention is directed to overcoming one or more of the
problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the present invention, an apparatus for sensing an
obstacle in the path of a vehicle is provided. The vehicle has a
power supply, a vehicle control circuit, and a vehicle brake and
brake control circuit. A plurality of radiant energy receiving
devices are optically responsive to respective radiant energy
emitting devices. Each optically responsive set of emitting and
receiving devices is positioned along the vehicle at a location
sufficient to cause an obstacle in a respective path of the vehicle
to interrupt the reception of radiant energy by the respective
radiant energy receiving device. First and second interruptable
devices controllably connect the power supply to the brake control
circuit in response to each of the radiant energy receiving devices
continuing to receive radiant energy from the respective radiant
energy emitting device, and disconnect the power supply from the
brake control circuit in response to any of the receiving devices
failing to continue to receive the radiant energy from the
respective emitting device.
In a second aspect of the present invention, an apparatus for
detecting failure of the obstacle sensing device associated with a
vehicle is provided. The optical sensing device has a plurality of
radiant energy emitting devices, each associated with a respective
radiant energy receiving device, and the vehicle has a power supply
and a vehicle brake and brake control circuit. The vehicle control
unit controllably produces first and second energization signals in
response to a predetermined condition of the vehicle. First and
second switches receive respective ones of the first and second
energization signals, and responsively controllably supply
electrical power from the power supply to predetermined ones of the
radiant energy emitting and receiving devices. First and second
solenoid coils are each serially connected to respective first and
second sets of receiving devices. First and second electrical
contact sets are serially connected between the power supply and
the brake control circuit, each of the first and second electrical
contact sets being responsive to a respective one of the first and
second solenoid coils.
The present invention provides a obstacle detection apparatus that
utilizes optical elements for detecting the presence of an
obstacle. The obstacle detection device is advantageously
associated with a fault detection circuit sufficient to produce a
fault signal in response to detecting various undesirable
conditions of the obstacle detection system. The fault detection
circuit operates in response to a predetermined condition of the
vehicle.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present invention, reference may
be made to the accompanying drawings, in which:
FIG. 1 is a schematic diagram of an apparatus incorporating one
embodiment of the present invention;
FIG. 2 is a partial top plan view of a vehicle incorporating one
embodiment of the present invention;
FIG. 3 is a partial top plan view of a vehicle incorporating a
second embodiment of the present invention; and
FIG. 4 is a flowchart of a software program module used in one
embodiment of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring to the FIGS., an apparatus employing certain of the
principles of the present invention is generally indicated by the
reference numeral 10. It should be understood that the following
detailed description relates to the best presently known embodiment
of the apparatus 10. However, the apparatus 10 can assume numerous
other embodiments, as will become apparent to those skilled in the
art, without departing from the appended claims.
A vehicle control circuit 12 is associated with the apparatus 10.
The vehicle control circuit 12 is, for example, a microprocessor or
other logic control unit associated with a vehicle 13. The vehicle
control circuit 12 is capable of producing and receiving electrical
signals as is known in the art.
A power supply 14, and vehicle brake 16 and brake control circuit
18 are also associated with the vehicle 13. The vehicle brake 16
is, for example, an electrical brake having an associated brake
excitation coil 20. The coil 20 is controllably connected to the
power supply 14, and is connected through a voltage divider 21 to
the vehicle control circuit 12. In response to at least a
predetermined magnitude of current flowing through the coil 20, the
vehicle brake 16 is disengaged. In response to less than the
predetermined magnitude of current flowing through the coil 20, a
spring system (not shown) causes the vehicle brake 16 to engage,
stopping the vehicle, as is well-known in the art. Assuming that
power is provided to the coil 20, the magnitude of current flowing
through the coil is controlled by a transistor switch 22 in
response to pulses received from the vehicle control circuit 12
through a resistor 24.
A plurality of sets 26a-d of radiant energy emitting devices 28a-d
and radiant energy receiving devices 30a-d are associated with the
apparatus 10. Each radiant energy receiving device 30a-d is
optically responsive to a predetermined respective one of the
radiant energy emitting devices 28a-d and is positioned along the
vehicle at a location sufficient that an obstacle in a respective
path of the vehicle interrupts reception of the radiant energy by
the respective responsive radiant energy receiving device 30a-d. In
the preferred embodiment, the radiant energy emitting devices 28a-d
are infrared light emitting diodes, and the radiant energy
receiving devices 30a-d are infrared responsive
phototransistors.
First and second interruptable devices 32,34 controllably connect
the power supply 14 to the brake control circuit 18 in response to
each of the radiant energy receiving devices 30a-d continuing to
receive the radiant energy from the respective radiant energy
emitting device 28a-d, and disconnect the power supply 14 from the
brake control circuit 18 in response to any of the radiant energy
receiving devices 30a-d failing to continue to receive the radiant
energy from the respective radiant energy emitting device 28a-d.
The first interruptable means 32 includes a first solenoid coil 32a
serially connected with a first set 30a, 30b of the plurality of
radiant energy receiving devices 30a-d. The second interruptable
means 34 includes a second solenoid coil 34a serially connected
with a second set 30c, 30d of the plurality of radiant energy
receiving devices 30a-d. The first and second interruptable means
32,34 also include respective first and second electrical contact
sets 32b, 34b serially connected between the power supply 14 and
the brake control circuit 18. Each of the first and second
electrical contact sets 32b, 34b is responsive to a respective one
of the first and second solenoid coils 32a, 34a.
A logic means 36 controllably produces a fault signal in response
to failure of at least one of the radiant energy emitting devices
28a-d the radiant energy receiving devices 30a-d, the first and
second solenoid coils 32a, 34a, and the first and second electrical
contacts 32b, 34b. The logic means 36 includes a logic gate 38
having a first input terminal a connected to one of the first and
second electrical contact sets 32b, 34b, a second input terminal
38b connected to the other of the first and second electrical
contact sets 32b, 34b, and an output terminal 38c connected to the
vehicle control circuit 12. First and second resistors 40,42 are
serially connected between the first and second input terminals
38a, 38b and the power supply 14. Each of the input terminals 38a,
38b is also connected through a filter circuit 44 to circuit
ground.
A first transistor switch 46 is connected through a resistor 48 to
the vehicle control circuit 12. The transistor switch 46 supplies
electrical power from the power supply 14 through a steering diode
50 to the optical emitting devices 28a, 28c. A second transistor
switch 52 is likewise connected through a resistor 54 to the
vehicle control circuit 12, and supplies electrical power from the
power supply 14 through a steering diode 56 to the optical emitting
devices 28b, 28d. The optical receiving devices 30a-d are connected
directly to the power supply 14.
Industrial Applicability
Operation of the apparatus 10 is best described in relation to its
use on a vehicle 13, for example, an automatic guided industrial
lift truck. Referring to FIG. 2, a fragmented top view of a vehicle
is shown to include first and second sets 26a, 26b of radiant
energy emitting and receiving devices. First and second
retroreflectors 60,62 are associated with respective ones of the
sets 26a, 26b of emitting and receiving devices. The sets 26a, 26b
and retroreflectors 60,62 are arranged such that radiant energy is
delivered from each of the emitting devices along a respective side
of the vehicle 13 and is reflected back to the receiving device by
the respective retroreflectors 60,62. Therefore, intrusion of any
object into the path of the radiant energy causes the respective
receiving device to no longer receive the reflected signal.
FIG. 3 demonstrates an alternative embodiment of the apparatus 10,
wherein an emitting and receiving device set 26a is positioned
along a portion of the vehicle 13, and the respective
retroreflector 60 is positioned on a movable portion of a bumper
64. In response to contact between the bumper 64 and an external
object, the retroreflector 60 is moved out of position relative to
the set 26a of emitting and receiving devices, and the path of
reflected radiant energy is interrupted. In either of the
embodiments of FIGS. 2 and 3, additional sets 26a-d of emitting and
receiving devices and corresponding retroreflectors, as shown in
FIG. 1, are provided in a similar manner to permit detection of
obstacles along each of four sides of the vehicle 13, and are not
shown in order to simplify the diagrams.
Adverting now to FIG. 1, assume that the vehicle 13 is operating
normally. The first and second energization signals are produced by
the vehicle control circuit 12 and delivered through the resistors
48,54 to the respective transistor switches 46,52. Responsively,
power is delivered from the power supply 14 through the transistor
switches 46,52 to each of the emitting devices 28a-d. Assuming that
no obstacle is blocking radiant energy from any of the respective
receiving devices 30a-d, power flows through the energy receiving
devices 30a, 30c, the solenoid coils 32a, 34a, and the receiving
devices 30b, 30d to circuit ground.
In response to energization of the solenoid coils 32a, 34a, the
respective electrical contact sets 32b, 34b are moved to the
normally open position, and electrical power is delivered from the
power supply 14 through each of the serially connected electrical
contact sets 32b, 34b to the brake control circuit 18. In response
to the vehicle control circuit 12 delivering pulses through the
resistor 24 to the transistor 22, current is delivered through the
brake solenoid coil 20, disengaging the vehicle brake 16.
Therefore, in response to normal operating conditions, the vehicle
brake 16 is disengaged and the vehicle 13 is controllably operable
according to various speed and direction parameters delivered from
the vehicle control circuit 12, as is known in the art.
In response to interruption of the radiant energy delivered from
any one of the emitting devices 28a-d to the respective receiving
device 30a-d, at least one of the receiving devices 30a-d is biased
"off", and current flow through the associated solenoid coil 32a,
34a ceases. Responsively, the associated electrical contact set
32b, 34b is moved to the normally closed position and current flow
from the power supply 14 to the brake control circuit 18 ceases.
Since the brake solenoid coil 20 is no longer connected to the
power supply 14, the vehicle brake 16 is spring applied to stop the
vehicle 13. The presence or absence of the connection from the
power supply 14 to the brake control circuit 18 is detected through
the voltage divider 58 by the vehicle control circuit 12. This
information can be advantageously used to determine the status of
the electrical contact sets 32b, 34b during operation of the
vehicle 13.
In response to any one of the radiant energy emitting devices
28a-d, the radiant energy receiving devices 30a-d, and the solenoid
coils 32a, 34a failing in an open circuit mode, or to interruption
of any of the connecting wires between the various devices and the
vehicle control circuit 12, at least one of the electrical contact
sets 32b-34b reverts to the normally closed position. Therefore,
failure protection for open circuits is automatically assured by
the structure of the apparatus 10.
Failure of one of the radiant energy receiving devices 30a-d in a
short circuit mode, or failure of one of the electrical contact
devices 32b, 34b to revert to the normally closed position upon
being deenergized, is detected automatically upon each start up
cycle of the vehicle. The software module set forth in FIG. 4 is
one example of a computer program flowchart sufficient to implement
such automatic detection. From this flowchart, a programmer of
ordinary skill can produce a set of computer instructions usable in
conjunction with the vehicle control circuit 12. Although a
properly programmed computer in accordance with the flowchart of
FIG. 4 is considered the best mode for performing the automatic
fault detection, those skilled in the art will recognize that other
computer programs, and hard logic circuits not incorporating a
computer, can be readily substituted in the vehicle control circuit
12.
Referring now to the schematic of FIG. 1 and the flowchart of FIG.
4, assume that the vehicle 13 is stopped. Entering the flowchart at
the "START" block 100, the radiant energy emitting devices 28a-d
are turned "off" in block 102 by the application of appropriate
energization signals to the first and second transistor switches
46,52. Responsively, each of the electrical contact sets 32b, 34b
is in the normally closed position, and the vehicle brake 16 is
spring engaged. The power supply 14 is connected through the first
electrical contact set 32b and the resistor 40 to the logic gate
first input terminal 38a. Likewise, the power supply 14 is
connected through the resistor 42 and the electrical contact set
34b to the logic gate second input terminal 38b. Responsively, the
logic gate 38 produces a logic "low" signal at the output terminal
38c which, in turn, is delivered to the vehicle control circuit 12.
This signal is examined in the block 104. If the logic "low" signal
is not produced, program control progresses to the block 106 where
a fault signal is produced, and onto the block 108 where the
vehicle 13 is stopped and/or other appropriate action is taken.
Assuming that the logic "low" signal is sensed in the block 104,
control passes to the block 110 where the first energization signal
is delivered from the vehicle control circuit 12 to energize the
first transistor switch 46 while leaving the second transistor
switch 52 de-energized. Responsively, power is supplied to the
radiant energy emitting devices 28a, 28c but not to the emitting
devices 28b, 28d. Assuming that neither of the radiant energy
receiving devices 30b, 30d has failed in a short circuit mode, the
serially connected solenoid coils 32a, 34a remain de-energized and
no change occurs in the logic "low" signal delivered at the output
lerminal 38c of the logic gate 38. This is determined in the block
112 where the continued presence of the logic "low" signal causes
program control to progress to the block 114. Should a failure have
occurred at this point, the logic "low" signal will not be present
at the block 112 and program control will instead proceed as above
to the block 106.
In the block 114, the state of the first and second energization
signals delivered from the vehicle control circuit 12 is reversed,
de-energizing the first transistor switch 46 and energizing the
second transistor switch 52. Responsively, power is delivered to
the radiant energy emitting devices 28b, 28d but not to the radiant
energy emitting devices 28a, 28c. Assuming that no short circuit
conditions exist in the receiving devices 30b, 30d associated with
the energized emitting devices 28b, 28d, neither of the solenoid
coils 32a, 34a is energized and the logic signal delivered from the
logic gate 38 remains at a logic "low" state. The continued
presence of the logic "low" signal is sensed in the block 116 and
causes program control to progress to the block 118. Failure to
continue to receive the logic "low" signal at the block 116 instead
causes program control to proceed to the block 106, as described
above.
In each of the above situations, an electrical contact set 32b, 34b
that has failed by remaining in the normally open position when the
associated solenoid coil 32a, 34a is de-energized, causes the logic
gate 38 to produce a logic "high" signal at the output terminal
38c. Responsively, the presence of the logic "high" signal (or
absence of the logic "low" signal) is detected in one of the blocks
112,116 as described above, and the fault signal is produced at the
block 106.
Assuming that no faults are detected up to this point, each of the
radiant energy emitting devices 28a-d is turned "on" by application
of the first and second energization signals in the block 118.
Responsively, each of the solenoid coils 32a, 34a is energized and
the associated electrical contact sets 32b, 34b are switched to the
normally open position. The logic gate 38 therefore produces a
logic "high" signal at the output terminal 38c. The signal is
received by the vehicle control circuit 12 and sensed at the block
120. Assuming that the logic "high" signal is received, program
control passes to the block 22 wherein normal operation of the
vehicle 13 commences. Should the logic "high" signal not be
received at the block 120, program control instead progresses to
the block 106 where the fault signal is produced.
The apparatus 10 provides collision detection for obstacles
entering the path of the vehicle 13 from any direction. Both open
circuit and short circuit fault conditions are automatically
detected.
Other aspects, objects, advantages and uses of this invention can
be obtained from a study of the drawings, the disclosure, and the
appended claims.
* * * * *